Height-adjustable interior floor wastes are known from Jay R Smith Mfg. Co. of Montgomery, Ala., USA. These provide a waste body which can be recessed into a floor and which is connectable to a drain, a grid cover for waste water to pass into the waste body, and a cover support which is screw-threadingly engaged with the waste body to enable height-adjustment of the grid cover relative to the waste body.
A height-adjustable shower or bathroom floor waste is also known from Impey UK Ltd of Ilton, Somerset, United Kingdom. This provides a waste body which is supported in a floor, a grid cover, and a cover support having a generally serrated or multi-ramped lower edge. Complementarily angled surfaces are provided on the waste body and on which the cover support sits. As the grid cover support is rotated in the waste body, the abutting ramp surfaces slide relative to each other, causing the cover support to telescopically extend or retract.
The problems associated with both of these arrangements is that, once the height of the cover has been adjusted and set, there is no means for preventing the height again changing, such as through use or by people inadvertently scuffing or knocking the cover grid.
Furthermore, the cover support of the Impey floor waste is not vertically engaged with the waste body, it is only seated in the waste body to slide on the ramped surfaces. Thus, the cover support is easily dislodged or removed from the waste body.
A further problem associated with the latter known arrangement is that, although the grid cover is removable from the cover support to permit access into the interior of the waste body, once the waste is installed, the height of the cover support from the base of the waste body can no longer be precisely adjusted and set rigidly in position prior to the flooring being installed. This follows from the fact that, when finishing the floor, either with concrete screed or tiles, the floor extends up to and abuts the cover support adjacent to the cover grid. Further height adjustment cannot reliably take place to compensate for changes in finished floor levels at the time of installation of the flooring material, typically tiles.